China is experiencing the same thing with people with knives.
Prof. Joshua Miller, chair of Social Welfare Policy at Smith College, attributed the attacks to stress caused by "rapid social change, mass migrations, increasing disparities in wealth and weakening of traditions." Some sociologists believe some of these attacks may due to the PRC government's failure to diagnose and treat mental illness. The perpetrators may feel victimized by stress due to the rapid social changes in China during the last 10 years caused by the privatization and decreased social security of China's reform and opening period. During this time, more and more migrant workers from rural areas have moved to cities such as Shanghai to find jobs. However because they do not have social security (because of the hukou system), many of them do not have health insurance. Because of the financial crisis of 2007–2010, some have lost their jobs, which is stigmatized in China, and have had to return to their native villages jobless and unemployed. The choice of schools for most of the attacks means they could be copycat crimes.
After a mass shooting in The Netherlands, a leading German sociologist (the name escapes me at the moment) basically said stricter gun laws don't help because it distracts from the real issues, like access to mental health, the stigma of seeking help, social isolation etc. That isn't to say our gun laws are ideal, but I'm kind of reminded of the knee jerk reaction to Toronto's July shoot out at a basketball game between a couple of gangsters that killed a couple of bystanders. Although the guns were not legally owned, registered, and had illegal magazines, the Toronto mayor's solution was to confiscate registered handguns from licensed owners. That maybe understandable or opportunistic, but it would be like putting a leg cast on someone with a sucking chest wound.